Is that Bambi heading off for shelter? (3)

I believe the answer is:
awn
'shelter?' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for awn that I've seen before include "Bristle on, eg, barley" , "Beard of plant" , "Stiff bristle on grasses" , "Beard growing from an ear of barley or rye" , "Bristle in flowering part of some grasses" .)
